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Plug-in hybrid electric vehicles emit nearly five times greater planet-heating emissions than lab-reported figures show, according to a recent analysis.

Widening Discrepancy In Lab and Real-World CO2 Output

Statistics reveals that PHEVs emit only 19% less CO₂ than traditional petrol and diesel cars, based on research conducted by a advocacy organization. That contrasts sharply with lab tests, which assumed a three-quarters decrease in emissions.

Researchers studied data from in-vehicle energy use monitors of eight hundred thousand cars sold in the EU from 2021 and 2023. They discovered that actual CO₂ output from PHEVs in 2023 were 4.9 times greater than official figures, up from 3.5 times in 2021.

“Real-world emissions are rising, while lab-reported figures are falling,” stated a lead researcher participating in the study. “This gap is growing and creates a significant issue. Consequently, PHEVs pollute almost as much as gasoline cars.”

Primary Factors Behind the Discrepancy

Analysts attributed most of the gap to inflated estimates of the “electric driving share” – the percentage of miles travelled in battery mode compared to total distance. They determined that only a quarter of driving was completed in electric mode, whereas lab estimates assumed over four-fifths.

Even, when operating in electric mode, pollution levels were well above official projections. This occurred because EV motors were insufficiently powerful sufficient to function alone, leading to combustion motors burning gasoline for nearly one-third of the distance completed in EV mode.

Policy and Financial Implications

Based on calculations, the lowballing of PHEV CO2 output enabled four major automaker groups to escape over €5bn in penalties from 2021 and 2023, by artificially easing adherence with EU fleet-average CO₂ standards.

Furthermore, drivers of PHEVs would spend approximately €500 extra annually in running expenses than is assumed under laboratory tests.

“The bold claims that automakers like to make about their plug-in hybrid cars are clearly far from the mark,” commented a transport expert. “Consumers are being misled into believing that by purchasing a PHEV, they are benefiting the planet and cutting money. In reality, PHEVs are only slightly improved than regular petrol and diesel cars in terms of energy use, CO₂ production, and operating costs.”

Political Debate and Automotive Lobbying

Plug-in hybrid cars have recently been brought again into political debates as carmakers have pressed the EU to weaken CO₂ targets. A planned ban on sales of new combustion engine vehicles in 2035 has faced heavy lobbying from the automotive industry and resistance from EU countries with significant car manufacturing.

Several senior politicians have proposed PHEVs as a potential “compromise” option to introduce in the legislation.

One independent energy policy expert, who was unaffiliated with the study, described the analysis a “very useful addition” after years in which segments of the car sector argued there was insufficient data to accurately assess actual emissions.

“These findings demonstrate, beyond any doubt, that the gap in official and actual PHEV energy use and CO₂ output is significantly larger than for gasoline or conventional vehicles,” they stated. “Any regulatory adjustments regarding PHEVs should be implemented with extreme caution and considering this evidence.”